As I had mentioned, many refer to the three mountains at Magic Kingdom- Space Mountain, Splash Mountain and last but not least Big Thunder Mountain. Big Thunder Mountain Railroad is a run away train and it is FAST!
Big Thunder Mountain Railroad is located back in Frontierland next to Splash Mountain. It has a height requirement of 44 inches. It can get very busy so you may need to get a FASTPASS or go early in day before line builds.
Make it your goal to go on ALL three mountains in one day, it’s great fun!! Enjoy!!